1. Field of the Invention
The present invention relates generally to vehicles and, more particularly, to an anti-theft vehicle system used to inhibit rotation of a vehicle wheel outside a predetermined spatial perimeter.
2. Description of the Related Art
It is sometimes desired to contain a vehicle within a predetermined spatial boundary or perimeter. In particular, retail stores are attempting to reduce the amount of lost vehicles such as shopping carts, which are either stolen or taken out of the normal bounds of the stores and not returned.
Accordingly, U.S. Pat. No. 5,194,844 to Zelda discloses a vehicle theft prevention system, which inhibits the use of a shopping cart once it is moved outside a boundary. This patented system includes an electronic wire that extends around and defines a perimeter of normal operating space, which is used by operators of a store's shopping carts. The electronic wire produces an electromagnetic field that is sensed by a sensor located adjacent one wheel of the shopping cart. The sensor sends a signal to a motor that moves a brake pad against the wheel of the shopping cart. Two limit switches are used to stop the motor when the motor has either moved the brake pad into or out of engagement with the wheel of the shopping cart.
One disadvantage of the above system is that it is relatively expensive because the motor must be large and two limit switches are needed. Another disadvantage of the above system is that the motor and brake pad are disposed outside of the wheel.
To overcome these disadvantages, U.S. Pat. No. 5,315,290 to Moreno et al. discloses a cart theft prevention system. This patented cart theft prevention system includes a mechanism disposed inside the wheel. The mechanism includes a radio frequency receiver and a solenoid device connected to the receiver, both of which are disposed inside the wheel. The solenoid has an armature to engage and disengage an opening in a non-rotating shaft. When the receiver detects that the cart has been moved outside the prescribed use area, the solenoid device is energized to drive its armature into the opening in the non-rotating support shaft supporting the wheel, thereby locking the wheel against rotation and immobilizing the cart.
One disadvantage of the above system is that it fully encases its components and battery in the rubber wheel compound making repair or battery replacement difficult. Another disadvantage is that the system uses an actuated pin that aligns with a bore in the stationary axle to lock the wheel, which requires a special wheel frame to accommodate the square-keyed axle bolt and secondly offers only two locking opportunities per revolution. Yet another disadvantage of this system is that it makes retrofitting to existing carts costly and difficult. Still another disadvantage of this system is that the manner in which the wheel locks is susceptible to misalignment and non-engagement, and if the wheel successfully locks, causes wear to occur at only two specific areas on the wheel tread surface. Therefore, there is a need in the art to provide an anti-theft vehicle system that overcomes these disadvantages.